Abstract [en]

A Monte Carlo simulation has been used to estimate the dose and contrastadvantages of replacing radiographic cassette fronts fabricated fromaluminium with cassette fronts fabricated from low atomic number material(carbon fibre). The simulation used a realistic imaging geometry andcalculations were made both with and without an anti-scatter grid. Accountwas taken of the scatter generated in the cassette front and the effect ofbeam hardening on primary contrast. Dose and contrast were evaluated for arange of cassette front thicknesses and tube potentials (60-150 kV) as wellas for four examinations representative of situations with varying amountsof scatter. The results with an anti-scatter grid show a clear dose andcontrast advantage in all cases when an aluminium cassette front isreplaced with a low attenuation cassette front. The contrast advantage isdependent upon the examination and is generally greater for imaging bonystructures than for imaging soft tissue. If a 1.74 mm aluminium cassettefront is compared with a 1.1 mm carbon fibre cassette front, then the doseadvantages are 16%, 9%, 8% and 6% and the contrast advantages are 10%, 7%,4% and 5% for the AP paediatric pelvis examination at 60 kV, theanteroposterior (AP) lumbar spine examination at 80 kV, the lateral lumbarspine examination at 100 kV and the posteroanterior (PA) chest examinationat 150 kV, respectively. The results without an anti-scatter grid show anincreased dose advantage when a low attenuation cassette front is used, butthe contrast advantage is small and in some situations negative.